Yes, in the context of money, 7K is the same as 7000. The "K" in this case stands for "thousand," so 7K is shorthand for 7000. This notation is commonly used in financial contexts to represent large numbers in a more concise manner.
350 dollars is 7000 nickels.
3k-5=7k+73k-7k=7+5-4k=12k=-3
-6k+7k = 1k or normally k on its own.
7k + 4 + 4k - 9 - 5k (7k + 4k - 5k) + (4 - 9) 6k + -5 6k - 5
7000 X 7000= 49000000